摘要
为研究冻融循环作用下硫酸盐渍土热-质迁移规律及结构损伤机理,以河西走廊盐渍土为研究对象,在无压补给条件下进行冻融循环试验,并借助核磁共振和SEM(scanning electron microscope)试验分析冻融循环前、后硫酸盐渍土的孔隙结构损伤机理.研究表明:冻融循环作用下硫酸盐渍土内温度传递存在“深度效应”和“时间滞后效应”,时差约为5 h;冻结深度前期不断向下发展,后期逐渐趋于平稳,最大冻深为8.54 cm;溶液补给量随温度降低而增大,升高而减小;冻融循环240 h后水、盐含量在冻结区增大,非冻结区基本不变;盐渍土盐冻胀变形随温度变化呈周期性盐冻胀-融溶沉规律发展,且存在位移滞后温度效应;盐渍土经历一系列反复“冻结—冷凝—结晶—融化—溶解”过程后,中孔隙和大孔隙明显增多,并形成贯通的裂隙,土体结构由冻融前的片层状结构转变为絮状结构.
To study the heat–mass transfer patterns and structural damage mechanisms of sulfate saline soil under freeze–thaw cycles,a freeze–thaw cycle test was carried out under non-pressurized supply condition with saline soil from Hexi Corridor as the research object.The pore structure damage mechanism of sulfate saline soil before and after freeze–thaw cycles was analyzed using nuclear magnetic resonance(NMR)and scanning electron microscope(SEM).The study shows that temperature transfer in the sulfate saline soil under freeze–thaw cycles exhibits the“depth effect”and“time-lag effect”,with a time lag of about five hours.The freezing depth initially develops downward before stabilizing,reaching a maximum depth of 8.54 cm.The solution supply amount increases as temperature decreases and decreases as temperature rises.Water and salt content increase in the frozen zone after a 240-hour freeze–thaw cycle while remaining basically unchanged in the unfrozen zone.The deformation of saline soil due to salt-frost heave follows a cyclic pattern of“heave and thaw”,with a time lag in response to temperature changes.Repeated cycles of“freezing–condensation–crystallization–thawing–dissolving”cause significant increases in medium and large pores of saline soil,leading to interconnected cracks.The soil structure transitions from a laminar structure before freeze–thaw cycle to a flocculent structure afterwards.
作者
余云燕
罗崇亮
崔文豪
杜乾中
高远
张庭华
YU Yunyan;LUO Chongliang;CUI Wenhao;DU Qianzhong;GAO Yuan;ZHANG Tinghua(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China;School of Civil Engineering,Tianshui Normal University,Tianshui 741000,China)
出处
《西南交通大学学报》
北大核心
2025年第5期1090-1097,1120,共9页
Journal of Southwest Jiaotong University
基金
甘肃省科技计划项目(23JRRA854)
甘肃省教育厅高校教师创新基金项目(2024A-121)。
关键词
硫酸盐渍土
冻融循环试验
传热传质
盐冻胀变形
结构演变
sulfate saline soil
freeze–thaw cycle test
heat–mass transfer
salt-frost heave-induced deformation
structural transition
作者简介
第一作者:余云燕(1968-),女,教授,博士生导师,研究方向为岩土与地下工程、土-结构耦合动力学,E-mail:yuyunyan@mail.lzjtu.cn。
